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Thursday, July 24, 2008

We may all be space aliens

Genetic material from outer space found in a meteorite in Australia may well have played a key role in the origin of life on Earth, according to a study to be published Sunday. European and US scientists have proved for the first time that two bits of genetic coding, called nucleobases, contained in the meteor fragment, are truly extraterrestrial. Previous studies had suggested that the space rocks, which hit Earth some 40 years ago, might have been contaminated upon impact. Both of the molecules identified, uracil and xanthine, "are present in our DNA and RNA," said lead author Zita Martins, a researcher at Imperial College London. RNA, or ribonucleic acid, is another key part of the genetic coding that makes up our bodies. These molecules would also have been essential to the still-mysterious alchemy that somehow gave rise, some four billion years ago, to life itself. "We know that meteorites very similar to the Murchison meteorite, which is the one we analysed, were delivering the building blocks of life to Earth 3.8 to 4.5 billion years ago," Martins told AFP in an interview. Competing theories suggest that nucleobases were synthesised closer to home, but Martins counters that the atmospheric conditions of early Earth would have rendered that process difficult or impossible. A team of European and US scientists showed that the two types of molecules in the Australian meteorite contained a heavy form of carbon -- carbon 13 -- which could only have been formed in space. "We believe early life may have adopted nucleobases from meteoric fragments for use in genetic coding, enabling them to pass on their successful features to subsequent generations," Martins said. - continued on mysterytopia